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ENGINE CONTROL USING COMBUSTION MODEL
Ohyama, Y. The Korean Society of Automotive Engineers 2001 International journal of automotive technology Vol.2 No.2
The combination of physical models of an advanced engine control system was proposed to obtain sophisticated combustion control in ultra-lean combustion, including homogeneous compression-ignition and activated radical combustion with a light load and in stoichiometric mixture combustion with a full load. Physical models of intake, combustion and engine thermodynamics were incorporated, in which the effects of residual gas from prior cycles on intake air mass and combustion were taken into consideration. The combined control of compression ignition at a light load and sparit ignition at full load for a high compession ratio engine was investigated using simulations. The control strategies of the variable valve timing and the intake pressure were clarified to keep auto-ignition at a light load and prevent knock at a full load.
Design Using Finite Element Analysis of a Switched Reluctance Motor for Electric Vehicle
Ohyama Kazuhiro,Nashed Maged Naguib F.,Aso Kenichi,Fujii Hiroaki,Uehara Hitoshi The Korean Institute of Power Electronics 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.2
In this paper, a Switched Reluctance Motor (SRM) employed in an electric vehicle (EV) is designed using the finite element method (FEM). The static torque of the SRM is estimated through magnetic field analysis. The SRM temperature rise over operation time is estimated through heat transfer analysis. First, static torque and temperature rise over the time of 600W SRM is included in the experiment set, and are compared with the calculated results using the FEM under the same conditions. The validity of the magnetic field analysis and heat transfer analysis is verified by the comparisons. In addition, a 60 [kW] SRM employed in an EV, whose output characteristics are equal to a 1500 [cc] gasoline engine, is designed under magnetic field analysis and heat transfer analysis.
AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at <i>z</i> ≲ 0.5
Ohyama, Y.,Wada, T.,Matsuhara, H.,Takagi, T.,Malkan, M.,Goto, T.,Egami, E.,Lee, H.-M.,Im, M.,Kim, J.H.,Pearson, C.,Inami, H.,Oyabu, S.,Usui, F.,Burgarella, D.,Mazyed, F.,Imanishi, M.,Jeong, W.-S.,Miya EDP Sciences 2018 Astronomy and astrophysics Vol.618 No.-
<P><I>Context.</I> Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift <I>z</I> ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy.</P><P><I>Aims.</I> We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to <I>z</I> ≃ 0.5, by paying particular attention to their PAH properties.</P><P><I>Methods.</I> We conducted a low-resolution (<I>R</I> ≃ 50) slitless spectroscopic survey at 5-13 <I>μ</I>m of 9 <I>μ</I>m flux-selected sources (>0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 <I>μ</I>m features at <I>z</I> < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 <I>μ</I>m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 <I>μ</I>m PAH feature over the 3.5 <I>μ</I>m stellar component of the SEDs.</P><P><I>Results.</I> The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 <I>μ</I>m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at <I>z</I> ≳ 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.</P>
Mitsuki Ohyama,Shoji Kudo,Shuntaro Amari,Hiroshi Takiyama 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.75 No.-
The quality of crystalline particles is determined by many kinds of characteristics. Therefore, it isnecessary to evaluate each characteristic comprehensively. In this study, the uniformity of eachcharacteristic of the crystalline particles was defined and proposed as performance index “homogeneity”,and the operation method of reaction crystallization for improvement the crystal qualities wasdeveloped. Homogeneity was evaluated by using the uniformity of particle size and crystal shape. Furthermore, in order to produce the crystalline particles with high homogeneity, it was necessary toconsider the effects of solution pH and the mixing methods of two solutions.
MODELING THE WAVE-INDUCED MOTION OF FLOATING BODIES
Takumi Ohyama 한국해안해양공학회 1999 학술강연회 발표논문초록집 Vol.2 No.1
New efficient models have recently been developed for the analysis of wave-induced motion of floating bodies. The basic wave equations and a wave-body interaction model adapted are given in vertically integrated form with plural vertical-dependence functions, which favorably reproduce the vertical profile of the wave-induced fluid motion. This achieves much higher computational efficiency as compared to conventional approaches where a boundary value problem for the velocity potential is directly solved. The basic performance of these models is demonstrated via comparisons with other analytical and numerical models.
Design Using Finite Element Analysis of a Switched Reluctance Motor for Electric Vehicle
Kazuhiro Ohyama,Maged Naguib F. Nashed,Kenichi Aso,Hiroaki Fujii,Hitoshi Uehara 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.2
In this paper, a Switched Reluctance Motor (SRM) employed in an electric vehicle (EV) is designed using the finite element method (FEM). The static torque of the SRM is estimated through magnetic field analysis. The SRM temperature rise over operation time is estimated through heat transfer analysis. First, static torque and temperature rise over the time of 600W SRM is included in the experiment set, and are compared with the calculated results using the FEM under the same conditions. The validity of the magnetic field analysis and heat transfer analysis is verified by the comparisons. In addition, a 60 [㎾] SRM employed in an EV, whose output characteristics are equal to a 1500 [cc] gasoline engine, is designed under magnetic field analysis and heat transfer analysis.